Q6
(a) Explain how static and dynamic imbalance of crankshafts can be overcome.
(5)
(b) Discuss the methods employed to obtain primary, reciprocating balance in an engine and explain why they are not completely successful.
(5)
(c) Describe engine additions which may be fitted to overcome problems resulting from primary or secondary imbalance.
(6)
Reference Answer
### (a) Static and Dynamic Imbalance of Crankshafts **1. Static Imbalance** * **Concept:** Static imbalance occurs when the center of gravity (CG) of the crankshaft does not lie on its axis of rotation. It is an imbalance in a single plane. When stationary, the heavy side will always rotate to the lowest point due to gravity. * **Effect:** During rotation, the eccentric mass generates a centrifugal force that acts radially outwards, causing the crankshaft to vibrate. This force rotates with the shaft and places a cyclic load on the main bearings.
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